1. Field of the Invention
This invention relates to a dynamical quantity sensor for detecting a dynamical quantity such as an angular velocity, acceleration, or the like.
2. Description of the Related Art
A tuning fork type device or a tuning plate type device using a piezoelectric device has been known in the past as a device for detecting a yaw rate by utilizing the Coriolis force.
However, such a device requires machining of a complicated shape and bonding of a piezoelectric device, and is not therefore free from the problems that the reduction of size and cost of production and accomplishment of higher precision are difficult. A yaw rate sensor according to the prior art comprises piezoelectric ceramics, for example, and detects the yaw rate by utilizing the Coriolis force, but it has been difficult to reduce size and the cost of production. To solve these problems, the inventors of the present invention have already proposed a yaw rate sensor having the construction which is shown in FIG. 1 of the accompanying drawings. In this construction, a vibrating direction 10 of a weight 1, a rotating direction 11 to be applied to the sensor and a detecting direction 4 of the Coriolis force obtained by such a rotation have a relationship such that they orthogonally cross one another.
On the other hand, the sensor device 1 must be vibrated in the vibrating direction 10 of the weight and the detecting direction 4 of the Coriolis force. Therefore, the sensor device 1 (that is, the weight) is constituted in such a manner that a supporting direction (the direction of the arrangement of a support member 2) coincides with a direction of the axis of rotation 7. In this construction, an electrode 6 for detecting the vibration must be disposed on a plane below the sensor device 1 opposing the first plane 8 of the sensor device. Accordingly, there remain the problems yet to be solved that the construction is complicated and the production is difficult.
It may be conceivable to form the second surface 9 of the sensor device 1 on the upper surface thereof but in such a case, the support member 2 must be disposed at a lower portion. In view of the production of the sensor device by micro-machining, however, it is quite impossible to accomplish the production method of such a sensor device.